as in treacherous
formal
causing harm in a way that is gradual or not easily noticed
Most people with this insidious disease have no idea that they are infected. an insidious enemy
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Example Sentences
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Recent Examples of insidious
One of the less insidious reasons people may choose to ghost a partner is to spare their feelings.
—
Mark Travers, Forbes.com, 18 Aug. 2025
Habitat loss has been insidious — croplands have been stripped of their bordering hedgerows and old fields and woodlots have been converted to housing developments.
—Bruce Beehler, Baltimore Sun, 17 Aug. 2025
The simplicity of the scheme What made the fraud so insidious was its simplicity.
—Erik Lie, Fortune, 17 Aug. 2025
Even more insidious is the ability of some perennial weeds to reproduce from little vegetative bits that break off, roll down the hill, and make new problems.
—Paul Cappiello, The Courier-Journal, 15 Aug. 2025
See All Example Sentences for insidious
Mark Travers, Forbes.com, 18 Aug. 2025
Habitat loss has been insidious — croplands have been stripped of their bordering hedgerows and old fields and woodlots have been converted to housing developments.
—Bruce Beehler, Baltimore Sun, 17 Aug. 2025
The simplicity of the scheme What made the fraud so insidious was its simplicity.
—Erik Lie, Fortune, 17 Aug. 2025
Even more insidious is the ability of some perennial weeds to reproduce from little vegetative bits that break off, roll down the hill, and make new problems.
—Paul Cappiello, The Courier-Journal, 15 Aug. 2025
See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
Adjective
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Arriving home in the dark after work or dinners out is inevitable, but finding the front door doesn’t have to be a treacherous experience for you or your guests.—
Maggie Horton,
PEOPLE,
8 Sep. 2025
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On the other hand, Will — played with a jagged sensitivity by Paul Mescal, making the most of his sad-eyed charisma and physical presence — is a guy who feels more at home at a desk, with only a candle to light his way through the treacherous creative process.—
David Fear,
Rolling Stone,
8 Sep. 2025
Adjective
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This planet is electric, unpredictable and genius with its approach, but its transits are anything but subtle.—
Valerie Mesa,
PEOPLE,
6 Sep. 2025
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Even subtle light or noise can disrupt sleep cycles, preventing you from reaching the deeper, most restorative stages of sleep necessary for physical and mental recovery.—
Bryan Robinson,
Forbes.com,
6 Sep. 2025
Adjective
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Representatives for James have called the fraud claims made against her politically motivated and false.—
Robert Faturechi,
ProPublica,
6 Sep. 2025
-
On the next play, Taylor was called for a false-start penalty.—
Pete Grathoff,
Kansas City Star,
6 Sep. 2025
Adjective
-
Agencies would review requests, balancing innovation against risks such as economic harm or deceptive practices.—
Paulo Carvão,
Forbes.com,
10 Sep. 2025
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There will be a temptation because of his height to draw parallels with Moyes’ use of Marouane Fellaini and Soucek, two key pillars of his Everton and West Ham sides, but where Rohl is concerned, his size can be deceptive.—
Patrick Boyland,
New York Times,
4 Sep. 2025
Adjective
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Her Ashley is the movie’s fourth and fifth wheel, dismissed as both a perfidious troublemaker and a New Age airhead—a life coach in need of a wife coach.—
Justin Chang,
New Yorker,
22 Aug. 2025
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This perfidious situation, unintentional as its creation may have been, was strongly critiqued as far back as 1983 by Jonathan Crush and Paul Wellings in an article in The Journal of Modern African Studies.—
The Editors,
JSTOR Daily,
15 Aug. 2025
Adjective
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This approach is unreliable because the proxy materials, like volcanic rock, might have been changed by geological processes or created long after the eggs were laid, resulting in incorrect age estimates.—
Mrigakshi Dixit,
Interesting Engineering,
11 Sep. 2025
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Poor labor management can also result in longer wait times, incorrect orders and ultimately negative reviews, directly impacting revenue.—
Jeff Kiesel,
Forbes.com,
10 Sep. 2025
Adjective
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Parasite The first non-English language film to win a Best Picture Oscar, Bong Joon-ho's Parasite centers on the Kims, who live on the wrong side of the tracks in Seoul, South Korea.—
Emy LaCroix,
PEOPLE,
8 Sep. 2025
-
Joveljic stepped up and placed the penalty kick into his right-hand corner, while goalkeeper Brad Stuver dove the wrong way.—
Daniel Sperry,
Kansas City Star,
8 Sep. 2025
Cite this Entry
“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 13 Sep. 2025.
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